In general, in an electrophotographic image forming apparatus such as a laser printer, a photosensitive drum configured to carry a developer image contacts with a transfer roller applied with a transfer bias for attracting the developer image. When a sheet passes through a space between the photosensitive drum and the transfer roller, the developer image moves toward the transfer roller, whereupon the developer image is transferred to the sheet, to thus form an image. Incidentally, in such an image forming apparatus, when the photosensitive drum is separated from the sheet at a position upstream of a transfer position (which is located between the photosensitive drum and the transfer roller) with respect to the direction of a conveyance of a sheet, a developer will disperse if electric discharge arises in the space, thereby staining the sheet with the dispersed developer (a so-called preliminary transfer).
In relation to such circumstances, JP-A-2005-128482 discloses bringing a leading end of a sheet into contact with a photosensitive drum by means of a guide plate formed from a flexible film and subsequently guiding the sheet toward a transfer position, thereby preventing occurrence of a preliminary transfer.
However, when a guide plate is formed from a flexible film as in the previously-described technique, the guide plate that has remained deflected thus far returns to its original position when a trailing end (an upstream end) of the sheet passes by the guide plate, thereby causing vibrations. This may generate a noise.